Most vehicles (automobiles, trucks, buses, and the like) have an AM/FM radio or other narrow band signal receiver. Many vehicles have a cellular or personal communication services (PCS) telephone or another spread spectrum communication device. The cellular and PCS telephones usually use code division multiple access (CDMA) technology. The radio and cellular or PCS telephone typically are each self-contained units, which essentially have all the components for independent operation.
There are several approaches for integrating an audio or radio device with a cellular or PCS telephone such that one or more components are used by each device. One approach provides the output of both the radio and the cellular or PCS telephone through the same speaker or output system. The radio usually is switched-off when an incoming call is received. Another approach is to switch-off other operating devices such as the radio when a voice-command detection circuit is activated. In a further approach, an incoming ring signal is detected and converted into another audio signal or sound at the headset or output device. The audio signal from the radio is turned off in response to the ring signal.